Carburetor



CARBURETOR Filed Nom 29, 1962 M m n 4. z 2. 3 5 0 G- 7 6 .a N n/ 678 I 2 6 0 666 2% M 2 v 8 `\.l| A? Z 2 5 www/0 3 6 2 4 H Wl w 3 0l 4 M 24. 4 6 Illu 44 f-||v|- M Fue.

mvmon OTTIS E. NEWMAN AGENT United States atei assunse transpireren ttls E. Newman, Normandy, Mo., assigner to ACF in dustries Incorporated, New York, NX., a corporation of New Jersey Filed Nov., 29, 1962, Ser. No. 246,999 Claims. (El. 2st- 34) This invention is directed to a carburetor and particularly to means for preventing adverse vapor conditions in certain fuel circuits of the carburetor.

@ne common trouble of most carburetors during operation under hot ambient weather conditions is the tendency of the fuel passages in the carburetor to boil out, which is that condition when fuel in a fuel passage is vaporized by high ambient temperature and forces solid (vapor-free) fuel out of the passage leaving substantially only fuel vapor therein. Such conditions exist predominantly after a fast hot drive, when the engine is stopped and stands for a period of time. With the vehicle motionless and the engine not operating, none of the cooling devices function to carry away heat from the engine. Accordingly, this heat, resulting from the fast operating conditions, will accumulate within the engine block and permeate all of the fuel lines adjacent thereto. With the carburetor mounted normally directly above the engine, the heat of the engine will also raise the temperature of the carburetor unduly and will vaporize fuel within the carburetor fuel passages. Vaporized fuel will set up vapor pressures which force solid fuel out of the passages into the mixture conduit of the carburetor or into the fuel bowl and out the various vents. The result is that upon starting the car there is little or no liquid fuel present in the critical fuel passages and it is necessary to pump the throttle lever or to crank the engine considerably until fuel is brought over from the fuel bowl to fill the carburetor passages.

It is therefore, an object of this invention to provide means wherein the vapor conditions in a carburetor under hot ambient conditions is alleviated.

lt is a further object of this invention to provide means in the carburetor for retaining solid fuel within the fuel passages under hot ambient conditions.

It is a further object of this invention to provide means in the accelerating fuel passages of the carburetor to retain fuel in the carburetor and prevent vapor conditions from being established due to high ambient temperatures.

One of the fuel circuits of the carburetor, in which Vaporization of fuel within the passages results in adverse engine operation is that of the accelerating pump. The accelerating pump is a fuel pump connected through a lost motion connection to the throttle. When the throttle is opened, the accelerating fuel pump is operated to force fuel through the accelerating pump passages into the mixture conduit to supply an additional amount of fuel for acceleration. This is particularly desirable during quick opening of the throttle for rapid acceleration of the vehiele. At this time, the accelerating pump forces a large quantity of fuel into the mixture passage for instant acceleration. Also, in starting, when the throttle is opened, additional fuel is forced into the mixture conduit through the accelerating fuel passages to aid in providing an enriched mixture.

When a hot vehicle has been standing for a period of time fuel vapor forming in the accelerating passages commonly forces fuel out of the passages into the mixture conduit or back into the fuel bowl. The accelerating fuel passages are thus emptied, so that fuel for starting is not available, but instead has been forced over into the mixture passage to flood the carburetor and engine manifold with an excessive amount of fuel, which further adds to the dimculty in starting the engine.

ICC

The invention specically is directed to the use of a fuel absorbent foam material placed in the accelerating pump cylinder and beneath the pump piston. This foam material retains fuel at all times within the pump cylinder and prevents its elimination by any vapor conditions that might exist, Thus, when the car is started or when the throttle is opened quickly, the piston will compress the foam material to force the absorbed fuel out of the foam and into the mixture passage for rapid starting or acceleration.

FGURE l is a plan view of a carburetor embodying the novel features of this invention.

FIGURE 2 is a longitudinal sectional view of the carburetor of FIGURE l shown mounted on an engine manifold.

FlGURE 3 is a partial sectional view of a modification of the invention.

The carburetor shown in FIGURES 1 and 2 consists essentially of a single casting iti, which is formed with aV fuel and air mixture conduit l2 and. a fuel bowl cover portion lli from which is integrally formed a depending portion formed with an accelerating pump cylinder i6 and accelerating fuel passage l@ and a fuel well structure As shown, the mixture conduit l2 is arranged and aligned vertically during operation and is connected by a flange 13 to the intake manifold M of an internal combustion engine E. ln the lower part of the conduit l?.

there is rotatably mounted a throttle valve 22 xed to a throttle shaft 2d journaled in appropriately aligned apertures in the body casing lil. A throttle operating lever 27 is iixed to shaft 2d for manual operation of the throttle through a throttle lever arm 29.

ln the upper portion of the fuel-air mixture conduit 12 there is similarly mounted for rotational movement an unbalanced choke valve 26 fixed to a choke valve shaft 2S, which is also iournaled in aligned apertures in the body casting ld. The top of the mixture conduit l2 is designed to be connected to an air filter through which passes air to the conduit l2 and engine E. Between the upper and lower portions of the mixture conduit l2 is formed a venturi or air llow restricting surface portion 30. A small booster venturi 32 is formed integrally with the body casting lil and has an inner venturi surface 34 coaxially aligned with the mixture conduit l2 and the primary venturi surface 3f).

A fuel bowl 36 is fixed beneath the fuel bowl cover 14 and is held with its rim tightly against a gasket 38, fitted between the rim of the fuel `bowl 36 and matching portions of the fuel bowl cover ld. A float 40 is fixed to a float lever il pivotally mounted on pin l2 journaled in a depending portion of fuel bowl cover i4. An arm 43 of the float lever di abuts one end of a flat `sided needle valve la having a tapered end extending into a valve seat of inlet fitting 46 to the fuel bowl 36 as is well-known in the art. The tting le connects the carburetor to a fuel line 4S. Fuel is forced under pressure by a pump Sil from a fuel tank 52, both schematically shown, through the fuel line 48 and into the carburetor inlet fitting 46. With the fuel level in bowl 36 low, the float lll is in a low position and lever arm 43 allows valve i4 to be pressed by fuel pressure to an open position. Fuel flows into the bowl 36 and when it reaches a predetermined level, the float rises and lever arm 43 presses against the needle valve id to close the inlet to the fuel bowl.

The lower end of the fuel well 2t) is closed by a pressed fitting 56 having a central orifice 69 therethrough, which is carefully formed to provide a metering jet for the flow `of fuel from the fuel bowl 3d to the mixture conduit l2. The upper end of the fuel well Ztl intercepts a cr-oss fuel passage 58 directed downwardly into the secondary venturi structure 32. A nozzle fitting titl is press-fitted into entrasse the end of passage 56 and has one end thereof extending into the center of the secondary venturi surface 3e. Pressfitted within the well 26 is a fuel emulsion tube 62 having apertures 63 therethrough along its length.

A metering pin 66 is suspended within the 'fuel well 26. Pin 66 has at its lower end an intermediate reduced portion 68 shown positioned within the main fuel jet orifice 69 and a larger portion 71 for operation in response to engine requirements. Flow of fuel through the main jet 56 is controlled by the metering rod 66 and in accordance with the rod portion 68 -or 71 within the jet 56. The metering rod 66 is supported from a retainer 76 in which the upper end of rod 66 is frictionally engaged.

The metering rod 66 extends across the main fuel passage 58 and retainer 76 is attached to the center of a diaphragm 76 sealed at its periphery across the bottom of a recess 86, which is closed by a metal cap $32 pressed into the top of the recess. A spring Sift between cap S2 and diaphragm 76 biases the diaphragm downwardly, as viewed in FIGURE 2. A passage 85 is formed through the body casting to the flange portion 13 of the carburetor and opens at 86 `into the mixing conduit and mani fold M below or downstream of the throttle 22 to connect the space above the diaphragm 76 to the manifold pressure of the engine.

Mounted within the cylindrical recess 16 formed in body casting 1t) is a pump piston 166, which is connected to a pump piston rod 192. A spring 11194 is fitted between a large washer 165 used as a cover for the fuel bowl vent tube 113. Washer 105 rests on a shoulder of rod 162 and the end 166 of an operating lever 168 (FIGURE l). Spring 104 surrounds a reduced portion 107 of rod 162 along which washer 165 freely slides. The lower end of the pump cylinder 16 is closed by a fitting 1119 having a central aperture 111 therethrough above which, biased by gravity, is a ball Valve 116. A fuel passage 112 extends between the pump cylinder 16 and the cylindrical passage 18 formed in the depending body portion 10. Passage 112 permits fuel flow into a fitting 114 closing the lower end of passage 18 and having at Aits upper end a Valve seat in which the pointed end of a gravity biased check valve 116 is fitted. The other end of passage 18 is fitted with a nozzle tube 118 through which fuel can be ejected from the passage 18 into the mixture conduit 12 under pressure from the pump piston 160.

Operating lever arm 168 is journaled at 121i on the carburetor body. The other end 122 of lever 168 depends downwardly (FIGURE 2) and is loosely connected to lost motion linkage 124 fixed to an arm 126 of the throttle lever 27. Movement of throttle lever 27 to open the throttle 22, swings lever arm 126 outwardly to load spring 125 which presses against lever end 122 to rotate lever 108 and press lever arm 106 downwardly toward the top of fuel bowl cover portion 14.

The operation of the structures described are as follows: Fuel from the fuel bowl 36 ows into both the pump cylinder 16 and the well structure 26, to fill these recesses to the level of the fuel in the bowl. Upon the turning over of the engine, air is sucked through the air filter into the mixture conduit 12 and the intake manifold M. The iiow of air through the booster venturi 32 provides a sub-atmospheric pressure within the venturi surface 34 which extends back through the fuel passage 56 to the upper end of fuel well 26. The atmospheric pressure on the surface of the fuel within bowl 36 raises the fuel within the well and simultaneously air is sucked through a restricted .passage provided for this into the upper portion of the fuel well. This air passes around and through the emulsion tube 62 to mix with the fuel and its vapor and to form an air-'fuel emulsion. The emulsion as carried upwardly from the fuel well into the main fuel passage 58 and out the nozzle 66 to form a fuel and air mixture within the mixture conduit 12.

At low engine speeds, the throttle 22 is partially closed so that the manifold vacuum in the intake manifold M below the throttle 22 is relatively high. This vacuum is effective through the passage 35 upon the upper surface of diaphragm 76 so that atmospheric pressure against the under surface of diaphragm '76 will press the diaphragm upwardly and carry the metering rod and its retainer 70 with it in an upward direction. This brings the thicker portion '71 of the metering rod end into the narrow top of jet orifice 69 to cut down the flow of fuel through this orifice in accordance with the lower engine speed. As the throttle 22 is opened progressively from low speed to high speed, the vacuum pressure in the manifold drops and spring d4 biases the diaphragm 76 and the metering rod 66 downwardly and retains the reduced portion 68 of the rod 66 in the jet orifice to provide a greater flow of fuel into the mixing conduit 12.

Spring 124 provides a lost motion yconnection between the accelerating pump rod 162 and the throttle lever 27. Any opening of throttle 22 by lever 27 simultaneously loads the spring 1126, which through lever 168 presses the accelerating pump piston 166 downwardly and forces fuel out of the lower portion of the pump cylinder 16 through passage 112 upwardly past the gravity lbiased valve 116 and into the upper portion of passage 118. This accelerating fuel under pressure will be directed into the nozzle structure i118 to provide additional fuel for the increased air flow due to the opening of the throttle 22. The act-ion of spring 124, loaded by the opening movement of the throttle, provides extended iiow of the accelerating fuel.

The choke valve v26 is controlled during cold weather and during cold starts by a thermostatic choke control device enclosed in a housing structure 130. This choke control is of a well-known design and as it does not constitute a part of this invention, it is not further described.

The end 166 of the rod arm 108 rests upon a small shoulder of rod 1112. Thus, when the throttle 27 is operated the linkage between throttle lever 27 and the rod 10S wil-l press the end of the rod 106 downwardly and `force the piston rod 162 along with it. The large washer 165 ts down over the upper end of the fuel bowl vent and closes it while the throttle is open, Spring 104 is compressed between rod end 166 and keeps the bowl vent 113 closed during throttle operation. Upon the release of the throttle lever 27, a throttle return spring normally attached to the linkage between the accelerator and the throttle lever 27 will return the throttle lever toward a closed position. Also, the spring 104 will aid to raise the piston rod 162 upwardly.

As described above, one chron-ic ailment of carburetors of the type described is the boil-out condition which can exist after a hot run of the engine followed by a period of standing with no means for cooling the engine and carrying away the heat generated by the engine operation. Such conditions normally occur during hot weather in the hot summer months. Accordingly, the heat of the engine is trapped temporarily, and raises the temperature of the engine and particularly the carburetor normally mounted on the engine. An excessive rise in temperature of the carburetor par-ts is sumcient to vaporize the large quantities of the fuel in the various fuel passages of the carburetor. This builds up vapor pressure in these passages, which forces the yliquid fuel out of the passages such as, for example, the passage 1S, from which the fuel flows out accelerating nozzle 113. Also, additional Vaporization of fuel beneath the piston 166 within the cylinder 16 forces fuel into passages 13 through the conduit 112, and this fuel, in turn, is forced by its vapor on out the nozzle 1,18. Thus a percolation effect is set up, in which fuel dribbles out the nozzle 118 into the mixture conduit 12 and runs down into the engine manifold M. The higher level of fuel in the fuel bowl 36 will force fuel back into the space in cylinder 16 which has been emptied by the percolation effect described. Thus, over a period of time a considerable amount of fuel can percolate through the accelerating fuel passages and into the mixture conduit 12 to excessively wet the engine manifold. This condition makes the starting of the car very difficult, if not impossible, because of the flooding of the engine.` Furthermore, since there is little solid fuel in the accelerating pump passages it takes additional pumping by throttle action to lill these passages for operation.

In accordance with the invention, to prevent these vapor conditions from occurring and to retain fuel within the accelerating fuel passages of the carburetor so that a condition of fuel percolation cannot exist, an amount of foam material i4@ is placed in the accelerating pump cylinder to fill the space between the piston ltil'i in its upper position and the closed end of the cylinder 16. One material which lends itself ideally to the requirements for proper operation is a polyurethane foam plastic, which is composed of an open cellular structure with high porosity. The foam material is such that fuel can how in and out of the material and also .to be retained therein by absorption. Since the foam material is readily absorbent, fuel is retained within the cylinder 16 to fill it completely except for the small spa-ce occupied by the solid portion of the foam. Upon operation of the throttle 22, the piston is pressed downwardly 4to compress the foam matcrial and squeeze the fuel out of the foam and through the accelerating passages to provide a desired accelerating fuel for the engine.

The presence of this foam material within the cylin er lo alleviates the vapor conditions existing during adverse hot ambient conditions as described, at which time fuel will normally percolate out of the accelerating fuel passages .into the engines manifold. However, because of the large absorption properties of the foam, the tendency of the Yfuel to vaporize has little or no effect in forcing the fuel Lout of the foam and into the fuel passages. Thus, even though fuel may be forced by its vapor out of the passages 18, no additional fuel will llow into these passages and thus provide a continuing percolation of fuel 1into the engine manifold. Furthermore, by retaining fuel within the accelerating cylinder i6, it is now immediately available for start-ing of the engine or immediate acceleration after starting.

The invention lends itself to an inexpensive construction of the fuel pump plunger 1B. For example, the pump plunger l@ shown in FIGURE 2 is of a well-known design and consists of a pump leather construction lill fitted around the pump plunger .litt to provide ia close fitting plunger and prevent fuel from escaping upwardly past the pump piston during a pumping stroke. The leather 101 is retained against the wall of cylinder le by a coil spring 103 in a conventional manner. However, with the use of the foam material 140 beneath the pump plunger, it is not necessary to utilize the detailed construction of the pump plunger shown in FIGURE 2. For example, in FIGURE 3 there is shown a simplified form of pump consisting of a plump rod l5@ hinged to a simple plunger 152, which can be of .any desired material, Isuch as a plastic or a metal, which lends itself to this function. The plunger 152. is fitted closely to the inner wall of the cylinder f6 and because of the lpresence of the foam material le@ beneath the plunger, it is not necessary to utilize the leather skirt construction to prevent fuel from escaping upwardly out of the cylinder. The foam material liti) itself retains suflcient fuel that downward movement of the plunger forces a greater part of this fuel through the accelerating fuel passage-s `and what little fuel may pass upwardly around the plunger 152 is negligible and can be ignored. rl`hus, the invention provides the adaptation of inexpensive pump construction to a carburetor, as described.

The material le@ has been described as a sponge-like foam material made of a polyurethane elastomer. This is the particular material which has operated very Well to provide the desired results. Such a material is one which is composed of strands connected by thin membrane-like passageways to provide a very porous and compressible material. The porosity of the material is not particularly critical and this material can be of any usable porosity which may range anywhere from 10 to pores per lineal inch. The porosity of the material can also be expressed as the resistance the material has to an air flow of 350 feet per minute through a 1/2 inch pad and which provides a resistance to the air flow of from 0.045 inch `to l inch of water. Such a'material, as made commercially, has approximately v97% of its total volume being void volume, which provides a large fuel holding capacity.

Although the particular polyurethane elastomer material described above has been one which is used successfully, it is also possible to practice the invention with other foam and sponge material, such as vinyl foam materials or sponge rubber. However, all such useable materials must, of necessity, be relatively unaffected by aliphatic hydrocarbons, as for example, they must not undergo any degree of swelling due to aromatics or other components of the fuel. The material. may be formed of a cellulose composition, or in fact, any sponge or foam material which readily functions as described above and which is substantially unaffected by being in contact for long periods of time with fuels.

The invention has been described with relation to a carburetor of the type disclosed in the figures and specication of this application. However, the invention need not be limited to this particular carburetor described, but can have utility in carburetors and fuel systems of different designs. Also, certain structures have been shown and described herein which will fulfill all the objects of the present invention, but it is contemplated that other modifications will be obvious to those skilled in the art which come within the scope of the invention as defined by the appended claims.

I claim:

l. A carburetor for an internal combustion engine comprising a body having a tubular mixture conduit therethrough, a fuel chamber for the storage of fuel and a fuel passage between said fuel chamber and said mixture conduit to provide for the delivery of fuel from said fuel chamber to said mixture conduit, said fuel passage including a fuel pumping chamber, pumping means movably mounted Within said pumping chamber, a compressible mass of fuel absorbent material positioned within said pumping chamber to be contacted and compressed by said pumping means, and a check valve in said fuel passage between said pumping chamber and said fuel chamber, said fuel passage including a portion forming an outlet from said pumping chamber for the ow of fuel from said pumping chamber under the action of said pumping means.

2. A carburetor for an internal combustion engine comprising a body having a tubular mixture conduit therethrough, a fuel chamber for the storage of fuel and a fuel passage between said fuel chamber and said mixture conduit to provide for the delivery of fuel from said fuel chamber to said mixture conduit, said fuel passage including an accelerating pump cylinder, an accelerating pump piston fitted and movably mounted within one end of said pump cylinder, means for moving said piston toward the other end of said pump cylinder, a compressible mass of fuel absorbent material positioned within and filling said other end of said pump cylinder in the path of movement of said piston to be compressed thereby, and a restriction in said fuel passage between said pump chamber and said fuel chamber, said fuel passage including a portion forming an outlet from said pump chamber for the flow of fuel from said pump chamber under the action of said pump piston.

3. A carburetor for an internal combustion engine comprising a body structure including a fuel and air mixture conduit therethrough and a fuel chamber spaced from said mixture conduit, a throttle movably mounted within said mixture conduit for movement from a closed to an open position, manual means connected to said throttle to operate said throttle in an opening movement, a fuel passage between said fuel chamber and said mixture conduit for providing fuel to said mixture conduit during engine operation, a second fuel passage between said fuel chamber and said mixture conduit for providing accelerating fuel to said mixture conduit, said second fuel passage including a p ump cylinder, a movable pump plunger within said cylinder and closing one end of said pump cylinder for pumping fuel through said second fuel passage, an inlet check valve in said second fuel passage between said fuel chamber and said pump cylinder for admitting fuel into said pump cylinder from said fuel chamber, said second fuel passage including an outlet opening at said other end of said pump cylinder for the flow of fuel from said pump cylinde-r to said mixture conduit under the action of said pump plunger, an outlet check valve in said second fuel passage between said outlet opening and said mixture conduit, a compressible mass of fuel absorbing material filling said pump cylinder in the path of movement of said plunger to be compressed thereby, and linkage means connecting said pump plunger to said throttle for simultaneous operation of said pump plunger to compress said absorbing material upon opening movement of said throttle by said manual throttle operating means.

4. A carburetor for an internal combustion engine comprising a body structure including a fuel and air mixture conduit therethrough and a fuel chamber spaced from said mixture conduit, a throttle movably mounted within said mixture conduit for movement from an open to a closed position, a fuel passage between said fuel chamber and said mixture conduit for providing fuel to said mixture conduit during engine operation, a second fuel passage between said fuel chamber and said mixture conduit for providing accelerating fuel to said mixture conduit, said second fuel passage including a pump cylinder, a movable pump plunger within said cylinder and closing one end of said pump cylinder for pumping fuel through said second fuel passage, said second fuel passage including an apertured wall closing the other end of said pump cylinder, an inlet check valve fixed to said apertured wall for admitting fuel into said pump cylinder from said fuel chamber, said second fuel passage including an outlet opening at said other end of said pump cylinder for the flow of fuel from said cylinder to said mixture conduit under the action of said pump plunger, an outlet check valve in said outlet opening, a compressible mass of fuel absorbing material filling said pump cylinder between said pump plunger and said apertured wall, and linkage means connecting said pump plunger to said throttle for simultaneous operation therewith.

5. The invention of cla-im 4 wherein said compressible fuel absorbent material comprises a polyurethane material having a porosity for the absorption of fuel.

References Cited by the Examiner UNITED STATES PATENTS HARRY B. THORNTON, Primary Examiner.

HERBERT L. MARTIN, Examiner. 

1. A CARBURETOR FOR AN INTERNAL COMBUSTION ENGINE COMPRISING A BODY HAVING A TUBULAR MIXTURE CONDUIT THERETHROUGH, A FUEL CHAMBER FOR THE STORAGE OF FUEL AND A FUEL PASSAGE BETWEEN SAID FUEL CHAMBER AND SAID MIXTURE CONDUIT TO PROVIDE FOR THE DELIVERY OF FUEL FROM SAID FUEL CHAMBER TO SAID MIXTURE CONDUIT, SAID FUEL PASSAGE INCLUDING A FUEL PUMPING CHAMBER, PUMPING MEANS MOVABLY MOUNTED WITHIN SAID PUMPING CHAMBER, A CONPRESSIBLE MASS OF FUEL ABSORBENT MATERIAL POSITIONED WITHIN SAID PUMPING CHAMBER TO BE CONTACTED AND COMPRESSED BY SAID PUMPING MEANS, AND A CHECK VALVE IN SAID FUEL PASSAGE BETWEEN SAID PUMPING CHAMBER AND SAID FUEL CHAMBER, SAID FUEL PASSAGE INCLUDING A PORTION FORMING AN OUTLET FROM SAID PUMPING CHAMBER FOR THE FLOW OF 